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Rich or Lean

I can't find my notes anywhere and I figure you guys answer faster then me cleaning up my office...
When you stab the throttle and it goes stumble, stumble, vroom. Is that too rich or too lean? No kids, I do not have my CO tester yet but there is a rule of thumb that my brain can't remember just now.

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Old 09-26-2011, 06:50 PM
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Think of the days of carburetors, when your mechanical excelerator pump was not squirting enough.

When you'd floor it, all would go silent for a fraction of a second, then the air flow would pull enough fuel through the venture, and POW it would snap to life....... lean condition.

However, if the opposite was true, you'd floor it, it would squirt to much fuel, and it would bog down, then slowly stumble back to life.....rich condition.

But then again these aren't carburetors now are they...hummmm.

Mark

Last edited by full quack; 09-26-2011 at 07:55 PM..
Old 09-26-2011, 07:53 PM
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Just installed my wideband and was way lean at idle (17.3) cruise and boost fine. While idling it would stumble then catch it's self and repeat. Once i richened it up it idle smooth.


Not the same situation, but I vote lean also. Just my .02 worth. I don't know why I waited so long too install though. I've also noticed I don't get as much popping now also, so maybe it changed my cruise aswell.
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Last edited by jly535; 09-26-2011 at 08:11 PM..
Old 09-26-2011, 08:09 PM
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I vote lean... mine does a little of that when it's still cold and the WUR has already gone through it's warm-up phase [15.9 AFR Cruise], but runs/cruises perfect [14.9 AFR] once the engine finally warmes up...
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Old 09-26-2011, 08:24 PM
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Very jumpy ride means lean usually if that helps
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Old 09-26-2011, 08:24 PM
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Lean (I had to wait for everyone else to clear the way...didn't want to be the first to risk a 50% chance of being wrong). If it didn't go "stumble stumble" and instead went "bog bog" the I would have said rich. I love technical descriptions....
Get back there, pull out your 3mm allen wrench, and tweak the mixture screw ever so little clockwise. One or two degrees out of 360 should do it. And of course, it that doesn't solve it, then tweak it ever so slightly the other way.
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Old 09-26-2011, 08:31 PM
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Quote:
Originally Posted by mark houghton View Post
Get back there, pull out your 3mm allen wrench, and tweak the mixture screw ever so little clockwise. One or two degrees out of 360 should do it. And of course, it that doesn't solve it, then tweak it ever so slightly the other way.
That was my plan Mark. LOL.
That is until the 3mm wrench jumped out of the sleeve and landed somewhere in the engine bay. For a minute I thought it went through the metering plate into the big hose. That was a heart stopper. After I shut him down and blew a fan on it for an hour, I found the wrench harmlessly sitting atop the turbo scavenge pump. Not sure how it got down there, but that was okay with me. Too late now to start tuning with a RarlyL8 special exhaust
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Old 09-26-2011, 09:00 PM
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BTW... I agree on the lean analysis. Same exact thing my Vespa did until I richened her up.
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Old 09-26-2011, 09:01 PM
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I got this hint from mooney265.

Quote:
wait until car fully warmed and then "slowly" push the idle mixture screw in. When you begin to feel pressure [the beginning of extra fuel being added], you'll need to notice your idle speed.
1. If it goes up initially, then your too Lean
2. If it goes down initially, then your too Rich
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Old 09-27-2011, 02:59 PM
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just remember, that suggestion only applies for "idle mixture" - - not cruise or boost mixture...
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Old 09-28-2011, 11:04 AM
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Yes that was idle mixture. Any neat hints for cruise or boost mixture mooney?
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Old 09-28-2011, 03:13 PM
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So I fattened it up to make it run pretty well. Only problem now is that it backfires like a MOFO when I shut it down. I'm talking neighbors running through the streets cause they thought it was gunfire. Five foot flames out of both pipes on the dual exhaust. It's almost embarrassing... almost but not quite. It's actually kind of awesome. However, the wife declared that it must not do that anymore when it made our 2 year old nephew start crying. Dang... something else to fix.
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Old 09-28-2011, 03:32 PM
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Good thing you don't live someplace like LA or The Bronx, 'cause most likely you would draw immediate fire (power) from those "innocent" neighbors. But I do think the 5 foot dual flames is way-cool, so fock those MOFO's if they can't take a joke.

Can't help much here without some CO or AFR info. It would appear you tweeked her a bit much toward the rich side. Checked your ignition timing lately?
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Old 09-28-2011, 03:50 PM
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Quote:
Originally Posted by oilonly View Post
Yes that was idle mixture. Any neat hints for cruise or boost mixture mooney?
wideband AFR sensor located right after the turbo - - with gauge to match... CIS gauges with ADJ-WUR with operating manual; allen wrench; pencil; and some patience...

Here is a good place to start with the factory specs: http://http://members.rennlist.com/jimwms/CIS/Testing/wur_specs.html
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Last edited by mooney265; 09-28-2011 at 05:20 PM..
Old 09-28-2011, 05:18 PM
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You guys are awesome. I was able to get everything running. Tomorrow I will try to post a video of the "shutdown backfire". Way more impressive in person though. I think my neighbor may have wet himself... I told him not to stand behind the car
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Old 09-28-2011, 06:22 PM
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intresting thread - wonder if its similar to mine

no idle probs or hot or cold start issues , however when starting off from cold if you blip throttle or try to accelrate hard it will 'stumble' about 2-2.5k rpm then continue , after driving for a bit and warming up this seems to disapear ??
also car pops a LOT when letting off the pedal espically if still in gear
is this a similar issue ?

cheers

johnny

forgot to mention its a 964 T 3.3
Old 04-01-2012, 02:24 PM
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Quote:
also car pops a LOT when letting off the pedal espically if still in gear
is this a similar issue ?
Is your decel valve (gold saucer shaped disk around 3 " in diameter) still connected? See my video below.

930 engine.3gp - YouTube
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Old 04-01-2012, 04:54 PM
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If I tune mine to be perfectly smooth at idle afrs are around 12~12.5.

I believe this to be too rich however by doing the push-the-meter-down-slightly method this is what it comes up with. Also any leaner and it doesn't idle smoothly. Maybe my meter isn't working properly or maybe some just like to run rich??
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Old 04-02-2012, 01:22 AM
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Quote:
Originally Posted by oilonly View Post
Is your decel valve (gold saucer shaped disk around 3 " in diameter) still connected? See my video below.

930 engine.3gp - YouTube
yep that sucker is still in there - could it have gone bad ?

cheers

J
Old 04-02-2012, 08:21 AM
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Quote:
Originally Posted by johnnycoo1 View Post
yep that sucker is still in there - could it have gone bad ?

cheers

J
If you are sure it is connected right like the one in my video then I say try another one. When I re-installed mine it reduced popping in a big way.

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Old 04-02-2012, 03:35 PM
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